Power transistors commonly employed in automotive and industrial electronics should have a low on-state resistance (Ron·A), while securing a high voltage blocking capability. For example, a MOS (“metal oxide semiconductor”) power transistor should be capable, depending upon application requirements to block drain to source voltages Vds of some tens to some hundreds or thousands volts. MOS power transistors typically conduct very large currents which may be up to some hundreds of amperes at typical gate-source voltages of about 2 to 20 V.
Compensation devices have been used in a voltage region of 200 to 800 V. In these compensation devices, the drift zone is implemented by a plurality of semiconductor layers having different conductivity types. Generally, new concepts of vertical power devices are being developed.
It is an object of the present invention to provide a semiconductor device comprising a transistor having improved properties.